A wireless device in a full-duplex communication system can simultaneously transmit and receive signals to support two-way communication. In a transmit path, a power amplifier amplifies a radio frequency (RF) signal for transmission. The transmit (TX) signal is routed through a duplexer and transmitted via an antenna. In the receive path, a desired receive (RX) signal is received via the antenna and coupled through the duplexer to a low noise amplifier (LNA). Following amplification by the LNA, the RX signal may be filtered and down-converted to baseband by a mixer. The down-converted RX signal is processed by other baseband components, such as a modem, to recover the received data.
In a full-duplex system, the TX path can interfere with the RX path. A portion of the TX signal may be coupled from the duplexer to the RX path, resulting in TX signal leakage. TX signal leakage can cause interference in the desired RX signal processed by the RX path. The interference may include second order distortion and/or cross-modulation distortion. The desired RX signal is a signal received via the antenna, in contrast to a TX signal received via leakage across the duplexer. Because the transmitter and receiver frequencies are different, the TX signal leakage can be rejected by filtering. Even with filtering, however, a residual amount of TX leakage can remain, causing degradation of the desired RX signal.